[Greenbuilding] Thermosyphoning water

[nick_pine at verizon.net]

Reuben Deumling wrote:

>Is that what Nick's numbers suggested? I tried to follow but got lost 
>somewhere...

Here's a more detailed example:

If a 4'x8' collector wants 0.04x32 = 1.28 gpm with a 10 F temp diff, and 
http://www.engineeringtoolbox.com/water-dynamic-kinematic-viscosity-d_596.html 
says the dynamic viscosity of 40 C (104 F) water is 0.653E-3 Pa-s, and 
http://www.calctool.org/CALC/eng/fluid/hagen-poiseuille says a 1"x8' pipe 
with a 1.28 gpm flow with an 0.00183 psi head, and 
http://www.engineeringtoolbox.com/water-density-specific-weight-d_595.html 
says 100 F water weighs 62 lb/ft^3, vs 61.71 at 110 F, then an 8' pipe with 
a 10 F temp diff would have an 8(62-61.71) = 2.32lb/ft^2 head, ie 2.32/144 = 
0.016 psi, about 10X more than the required head, if I did that right.

Nick